#define undo_width 16
#define undo_height 16
static unsigned char undo_bits[] = {
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0f,
   0xc4, 0x10, 0x2c, 0x20, 0x1c, 0x20, 0x3c, 0x20, 0x7c, 0x10, 0x00, 0x08,
   0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
